Nexus 7 (2013) or Lenovo Yoga 2 (8 inch)

Well, Lenovo Yoga 2 was launched this month only. So I am certainly sure update will have no problem. The device "should" get atleast one update if not more.

As far as looks is concerned that's a personal taste. But as far as specs go, despite the fact that N7 2013 is a year old, it still boasts of a good config. Atom processor which is in Yoga tablet is known to drain battery sooner than Qualcomm, but I guess Lenovo knows that and so to compensate they have provided a bigger battery.

So it comes down to your own personal choice, and requirement of the screen size. Since for me portability of 7" outweighs the design philosophy.

I sometimes think these companies give names to their products when high. Why does Yoga have to be both android and Windows. The 'pro' is the differentiator. Searching for a simple Lenovo Yoga 2 in google displays a bunch of pages related to the pro version with windows.

I am still unable to decide. That 4G spec is alluring which I am not going to get in Nexus 7 at that price as well as the microSD slot option. The resolution is also same and that specific Intel processor is at par with S4 Pro.

Not really sure what requirements you have, but 4G on a tablet seems less use for me. Also, GSMArena doesn't tell what LTE frequencies does Yoga tablet support. Not all frequencies which a device support is available on LTE in our country. For eg, Moto X support LTE 800 / 1800 / 2600 in India. But none of these frequencies have 4G available on them.

Coupled with the fact that LTE itself is still being developed here and will also be costly in initial phase, don't think you should buy a device solely on this factor.

As far as processing power both are on par with each other. But detailed review and comparison is still awaiting As per this article: AnandTech | Lenovo Launches Refreshes Of The Yoga Line.

Final decision : save some money and buy Nexus 9.

^ good and smart decision.